Empetrichthys latos

English Name:

Pahrump Poolfish

Original Description:

MILLER, R. R. (1948): The cyprinodont fishes of the Death Valley system of eastern California and southwestern Nevada. Miscellanous Publications, Museum of Zoology, University of Michigan No.68: pp 1-155

Holotype:

Collection-number: University of Michigan Museum and Zoology, Cat. No. UMMZ-141855.

The Holotype is an adult female, 43mm SL, collected by R. R. and F. H. Miller on 05.10.1942.

The species' name latos refers to the wide mouth of the species, as compared to Empetrichthys merriami. Latus (lat.) means broad; os (lat.) means mouth. Concerning to the subspecies' names, concavus refers to the concave profile between snout and occiput, whereas pahrump refers to the habitat, the valley in which this subspecies was found, and more particulary for the Pahrump Ranch, which is the more precise locality.

Synonyms:

none

Distribution and ESU's:

Empetrichthys latos has been endemic to three isolated springs in Pahrump Valley, which lie about seven miles apart. Each spring has been inhabited by one subspecies, mentioned in the contribution about terrae typicae. Water pumping in the second half of the 1950's drove the populations of Raycraft Ranch and Pahrump Ranch extinct. The introduction of other fishes into its native spring habitat contributed also to the decline of the Pahrump poolfish. For instance, Deacon et al. (1964) reported that the establishment of goldfish Carassius auratus in Manse Spring resulted in population depression.

The only remaining subspecies Empetrichthys l. latos was relocated from Manse Spring in the early 1970's to three introduction sites, when declining water levels due to groundwater pumping for agricultural development made the desiccation of Manse Spring predictable:

a) Los Latos Pool in an isolated canyon above the Colorado River (Soltz and Naiman, 1978). This site was flooded in the 1970's and its population got lost.

b) Corn Creek Springs, northwest of Las Vegas on the Desert National Wildlife Range, Nye County. The transplant to Corn Creek Spring took place in 1971 and involved 29 fish. Soltz and Naiman (1978) reported about relatively large reproducing populations there. They indicated that a third population was established in an artificial refugium in Ash Meadows but that it died out in 1977. The population in Corn Creek Springs was extirpated in the 1990's due to the introduction of crayfish and bullfrogs. In 2003 fish were reintroduced to a secure, but smaller part of Corn Creek Spring and seem to be stable there.

c) Shoshone Ponds, White Pine County, about 40 miles southwest of Ely. The ponds were stocked in 1972 with 16 Empetrichthys latos from Corn Creek or Manse Ranch Spring. The fish were extirpated in 1974 due to vandalism, but in 1976, another 50 fish were transplanted to the site. This population counted 1989 about 450 individuals.

In 1983 fish were introduced in unrecorded number to a reservoir at Spring Mountain Ranch State Park, Clark County, Nevada, after eradication of exotic species. Since then, this is the largest and most stable population of Empetrichthys latos. Estimations in 2004 reached nearly 30.000 specimens.

The crystal clear water of the species' type location had a constant temperature between 23°C and 25°C. The current was moderate. Miller noted "thick water cress (Nasturtium sp.), Chara, green algae and a fine-leaved Potamogeton" as vegetation. The water was shaded by cottonwood (Populus sp.) and willow.

Biology:

Despite the constant temperature of the type location, the fish is able to survive a wide range of temperatures, ranging from 4°C to more than 30°C.

At the type location spawning occured from January to July, with a peak in April or later in several habitats. The average brood size is 14 (up to 28), the eggs hatched in 7-10 days. Average length of the fry is 6.2mm.

Diet:

Empetrichthys latos is an opportunistic omnivore and feeds on a wide variety of available plant and animal material, especially algae and invertebrates. Taking in consideration a relatively short intestine ( about 1 1/2 times of TL), the biserial conical teeth with the outer series enlarged, this species seems to be rather carnivorous.

Size:

According to Miller (1948): 47mm (E. l. latos), 42mm (E. l. pahrump) and 39mm (E. l. concavus). The average size of the three subspecies only differs from 32mm to 35mm. Females are generally larger than males.

Colouration:

On its slender, elongate body, Empetrichthys latos shows a dark longitudinal streak, which tends to disappear in large adults. The colouration of the body is a greenish brown with dark blotches. Courting males may lose their spots and show a silver-blue, iron-like colour. Dorsal, anal and caudal fins are orange-yellow.

The subspecies designation is currently not in use, because the subspecies E. l. latos is the only remaining representative of this species. Pahrump spring went dry in the middle of the 1950's due to excessive groundwater pumping eliminating Empetrichthys latos pahrump and Raycraft spring was bulldozed and filled in 1955 killing all Empetrichthys latos concavus. The remaining subspecies latos could only survive through a couple of translocations so there is no Empetrichthys latos living in its original habitat.

Miller (1948) reported, that - including E. merriami - "some of the forms have an extremly small population, with effective breeding sizes as low as 50." As it looks like, E. merriami as well as E. latos concavus and pahrump disappeared before 1950.

Species of the subfamily Empetrichthyinae are oviparous fishes. Parenti (1981) proposed the Empetrichthyinae as sister group to the Goodeinae and used the name Goodeidae to encompass the two subfamilies. This narrow relationship has been supported by several studies since the 1980's (Webb, Domínguez).

Both genera of this subfamily share the lack of pelvic fins.

Empetrichthys latos is listed endangered by the U.S. Fish and Wildlife Service. Several actions have been taken to establish at least three stable populations of this species; this aim has not been achieved yet. In the USA, this species is subject to protection and may not be possessed by a person.

Obviously, at present this species is not available in Europe. A former introduction is uncertain.